There have been recent announcements of ATA-based storage systems aimed at the enterprise datacenter market. These products have been characterized as having two primary areas of application: As a secondary storage device or as a repository for fixed content or reference data. Certainly some overly enthusiastic marketing people are making claims for universal applicability. They would be wise to be more cautious. I believe the better understanding is that storage systems with ATA drives that have the functionalities needed in the enterprise datacenter space really do represent another layer in the storage hierarchy.
The storage systems that currently target secondary storage have some different requirements than those that are focused on reference data. Document retention is one of the reference data applications that requires adherence to specific rules and regulations to be legally acceptable. Those features necessary to meet those needs include retaining data in a read-only form (enforced in the storage system) for a defined retention period and control of access to the data through physical and electronic means. The secondary storage devices may require more of the remote copy and point-in-time copy functions that are in use with primary storage devices.
Vendors delivering these products include start-up companies as well as major vendors. We predict all the major vendors will have offerings this year and will dominate the sales in the enterprise datacenter space. How they are bringing the products to market is a more interesting topic. Major vendors (those with significant presence in the enterprise datacenter space) that have offerings include EMC, StorageTek and Network Appliance. EMC has different offerings to cover both the secondary storage and reference data markets.
It is very interesting that the secondary storage offering is an option for the CLARiiON devices where ATA drives can be chosen –– with the same feature/functions provided by the controller as when Fibre Channel drives are used. EMC has the Centera to cover the reference data market with specific capabilities required for that segment. The StorageTek offering uses a controller sourced from LSI with STK packaged ATA disks in a subsystem. The Network Appliance offering is based on their existing filer controllers (or heads in some terminology) with ATA drives for both markets with capabilities to address both.
Using secondary storage that incorporates ATA drives as an independent system that can have a mixture of both high-performance Fibre Channel disks and ATA disks presents another management challenge for the storage professional. Now there is another type of storage, another element in the storage hierarchy as we've discussed to decide on what data is stored there and how it is administered. The correct answer is to use the ATA storage as another storage class where capacity allocation is determined by the application requirements and placement is handled automatically. This is usually discussed as the provisioning function in an active storage resource management solution. The software must handle the different storage classes and storage systems that allow mixed of the drives types (even though they are uniform within a RAID group) must provide enough self-identification of the classes for the software to handle it with requiring administration customization.
There is real value to customers in using another category of storage. It must be managed with a degree of automation to get the maximum value. There are more products to come to market and the software to handle them is not universal. This will be an interesting space to watch.
This was first published in April 2003